1. Field of the Invention
The present invention relates to cleaning systems of semiconductor manufacturing apparatuses, and more particularly, to an air filtering device and a cleaning system of a semiconductor manufacturing system, which is capable of increasing productivity by replacing a filter in the midst of process.
2. Description of the Related Art
Recent rapid development on the semiconductor manufacturing technology brings about the active research to prevent a process error and increase a production yield. It is therefore essential to heighten an air purity level of a clean room, which can greatly influence the yield of semiconductors. The clean room is generally adapted to achieve as close to a particle-free environment as possible, and serves as an independent space from a peripheral environment to perform a wafer manufacturing process by suppressing a particle occurrence in a standard amount of air. To maintain proper controls, the clean room is isolated from the outside and is controlled independently of temperature and humidity. In the clean room, air capable of removing particles is circulated and supplied. The clean room is controlled to have an air purity level of about 1000 class or below, thereby containing about 1000 or less particles within 1 m3 thereof.
Further, a semiconductor manufacturing apparatus, in which a semiconductor fabricating process is performed, requires even better air purity, i.e., about 100 class or below, thereby containing about 100 or less particles within 1 m3. Thus, the semiconductor manufacturing apparatus is designed to receive clean air through a specific air cleaning system of the clean room.
For example, in an exposure apparatus that photosensitizes photoresist formed on a wafer, air of high purity must be supplied to fore and rear parts of a plurality of reduction lenses for reducing and projecting a predefined pattern formed on a reticle. Thus, an air filtering device is adapted to filter air supplied to an air supply line coupled to a housing (clean bench) that surrounds the exposure apparatus. Also, a fan for blowing air supplied through the air filtering device by a predefined pressure, and a muffler for reducing noise generated in the fan, are adapted therein.
However, when particles flow into the air filtering device through the muffler, the air filtering device may be polluted and its life shortened. Further, the air filtering device installed near the exposure apparatus is supplied at a high cost—e.g., more than tens of thousands dollars to remove micro particles and alkaline material.
Thus, to protect the air filtering device, another air filtering device to primarily remove the particles must be additionally disposed at a fore part of the fan, in place of the muffler. In this manner, the air filtering device disposed before the fan may reduce noise generated in the fan. Furthermore, the air filtering device disposed before the fan is easy to be exposed to the particles, so its life is short, and should be replaced frequently. However, it is difficult and costly to stop a semiconductor fabricating process to perform a filter replacement of the air filtering device.
An air cleaning system of a semiconductor manufacturing apparatus according to a conventional art is hindered by problems. First, a large quantity of particles flow through a muffler that is disposed at a fore part of a fan blowing air of predefined pressure to an air filtering device, which reduces noise of the fan. But as a result, the life of the air filtering device supplied at a high cost may be shortened with a resulting decrease in productivity. Second, in an air cleaning system of a semiconductor manufacturing apparatus according to a conventional art, the life of the air filtering device adapted at a fore part of the fan is shortened, causing a process of the semiconductor manufacturing apparatus to stop whenever a filter replacement of the air filtering device is required. This, in turn, causes a drop in productivity.